Field
The present disclosure relates to a method of effectively and economically removing siloxane compounds as impurities in biogas and an apparatus therefor.
Description of the Related Art
Biogas means gas including methane as a main ingredient which is a representative reusable fuel obtained through an anaerobic process with a microorganism or a chemical process by using a biomass such as straw, corn, sugar cane, or wood waste or organic wastes such as food waste, muck, or sewage sludge.
When the biogas of which the use is increased as a reusable energy source to replace coal fuel is used as for example, a vehicle fuel, emission of carbon dioxide is lower as about 80% than a gasoline vehicle, and emission of microdust and emission of nitrogen compounds and exhaust gas are significantly low. Further, the biogas discharges carbon dioxide to a similar extent to natural gas having a similar component, but since the entire process of generating and destructing carbon dioxide is circulated in the natural system and carbon emission is neutral, a total emission of carbon dioxide may be largely reduced even as compared with any coal fuel which irreversibly emits carbon dioxide in the air. Accordingly, in order to solve the problem of global warming caused by greenhouse gas, according to Paris agreement established in accordance with the U.N. convention on climate change for reducing the carbon emission quantity, several developed countries including Korea which should rapidly reduce a carbon dioxide emission quantity pay so much attention to the development.
The generation and use of the biogas may use organic waste which is naturally generated together production of food resources without requiring additional efforts, and the biogas has advantages of an eco-friendly process obtaining an energy source from waste resources which are generated in Korea and tipped on the land or the sea to cause environmental problems and using a natural gas infrastructure such as power plants which have been already invested in a large scale due to a similar property to the natural gas without a large change. However, since impurities such as siloxane in the biogas may cause problems such as engine abrasion and the like during power generation of a gas turbine, techniques of efficiently removing the impurities need to be developed and thus, the biogas can be used as fuels for power generation or transportation.
As the method for removing siloxane in the biogas, for example, a technique of an absorbing method by impregnated activated carbon like a carbon-based activated carbon absorbent disclosed in Korea Patent Registration No. 10-0964633 has been developed, but a scale of an absorption tower processing facility by a method of holding an absorbent to be used per year is excessively increased and maintenance costs required for replacement of the absorbent and the like has a large effect on economics of the biogas.
In order to solve the general problems of the carbon-based activated carbon absorbent, for example, deformed silicagel disclosed in International Patent Application Publication No. 2006/045561 and absorption and desorption techniques using activated alumina disclosed in U.S. Pat. No. 7,306,652 have been developed. However, unlike a case of absorbing water, in the case of absorbing the siloxane compounds, there are disadvantages that the reproduction is not easy and the economics is deteriorated because heat reproduction equipment or reproduction gas is required for reproducing the silicagel.
Meanwhile, in the case of an absorbing product as a material capable of replacing the silicagel, techniques for a super absorbing polymer have been developed. A polymer compound such as poly(meth)acrylate illustrated in Japanese Patent Application Publication No. 2009-183900 is a polymeric material which is widely used as an absorbing product due to an excellent ability of absorbing water like the silicagel, but has a disadvantage that it is not effective to remove a silica component in the biogas by a continuous process.
In the present disclosure, an effective silicagel replacement material and a process thereof capable of removing a silica component in the biogas have been developed by applying a technique for a desiccant formed by mixing a super absorbing polymer and a salt disclosed in Korea Patent Registration No. 10-0652903 (Dec. 4, 2006) as an absorbing product.